In general, an image reading apparatus such as a scanner has a backing at a position facing an image capturing device capturing an image of a document, and switches the position of the backing to change the background color of the document to white color or black color. The image reading apparatus drives the motor to pivot the backing to switch the position of the backing. Several methods are known as the method for setting the backing to a predetermined position.
For example, an image reading apparatus includes a position sensor for detecting the position of a backing, and when a position sensor detects the backing having moved to the predetermined position, the driving of the motor is stopped, and the backing is stopped at the predetermined position. However, in this case, the position sensor is required, which increases the apparatus size and the cost.
Alternatively, the image reading apparatus sets the backing to the initial position with a spring, and drives the motor to move the backing in a direction for compressing the spring, and continues to drive the motor so as to hold the backing at the predetermined position where the spring is most compressed. On the other hand, when the backing is returned back to the initial position, the image reading apparatus cuts off the power supply to the motor, and returns the backing from the predetermined position to the initial position with the force of the spring. However, in this case, since the spring is required, this increases the apparatus size and the cost, and since it is necessary to continue to drive the motor in order to hold the backing at the predetermined position, the consumed electric power increases.
Alternatively, the image reading apparatus sets the backing to the predetermined position by driving the motor by a certain amount defined in advance. However, when vibrations, shocks, etc., are applied to the image reading apparatus, the current position of the backing may change, and even when the motor is driven by a certain amount, the backing may not move to an appropriate position.
An image reading apparatus including a cleaning member capable of rotating a shaft member fixed to a brush sliding and cleaning a skimming glass arranged between a conveyed document and a scanner is disclosed. The image reading apparatus detects the home position of a cleaning member based on image information obtained from the scanner when the cleaning member is rotated (see Japanese Laid-open Patent Publication No. 2014-120785).
An image reading apparatus identifying the position of a carriage is disclosed. The image reading apparatus rotates the rotation body, and determines whether a rotation position detection mark is detected by an image sensor provided on a carriage, and identifies the position of the carriage based on the rotation angle of the rotation body when the rotation position detection mark is detected (see Japanese Laid-open Patent Publication No. 2014-72821).